The present invention relates to mineral recovery, and more particularly, to an improved drill section and method of hydraulically mining mineral deposits.
Hydraulic mining techniques have been commercially introduced which permit the mining and recovery of subterranean mineral deposits in an economical and environmentally safe manner. With specific reference to the recovery of high viscosity crude oil, such as from tar sand formation, these hydraulic mining techniques utilize a high velocity liquid which is discharged into the formation to dislodge the viscous crude oil and sand particles therefrom. The viscous crude oil, liberated from the tar and formation, forms an aqueous slurry which may be raised upward to the surface wherein the slurry may be processed by conventional systems to separate the viscous crude oil from the sand particles. Various examples of hydraulic mining tools are disclosed in the U.S. Pat. No. 3,951,457, issued to Redford, and my co-pending patent applications, Ser. No. 53,029, filed June 28, 1979, entitled "Down Hole Pump With Bottom Receptor", and Ser. No. 121,712, filed Feb. 15, 1980, entitled "Improved Hydraulic Mining Tool Apparatus".
Although such prior art hydraulic mining tools have proven to be a significant improvement over previous high viscosity crude oil recovering techniques, they all, to varying extents, possess certain structural integrity and drill shaft lubrication problems which detract from their operation efficiency. These problems become acute in the recovery of minerals from deep subterranean deposits.
The structural integrity problems in the hydraulic mining tool apparatus have typically been aggravated by the lack of an effective interconnection between the individual drill sections of the drilling string which can withstand the high structural forces developed during operation. The drill sections have typically been merely interconnected by a mating flange and bolt circle arrangement. Such connections permit communication between drill sections of plural conduits, such as a cutting jet conduit, a jet pump conduit, and an eductor slurry conduit, which must be properly aligned with similar conduits maintained within the interior of an adjacent drill section. Substantial pressure is generated by the tar sand formation falling in around the drill string during deep subterranean mining operations and substantial torque is generated during rotation of the drill string; however, such high tortional forces have heretofore resulted in intermittent shutdown of the drilling operation or, in extreme instances, has caused a complete structural failure or a twist-off of one of the individual drill sections connected by prior art bolt and flange arrangements. Intermittent discontinuance of the drilling operation significantly decreases overall operating efficiency. A twist-off condition typically results in the relatively expensive mining tool being irretrievably lost within the tar sand formation.
Further, the hydraulic mining tool apparatus of the prior art has heretofore been completely void of any means for lubricating the drill string during the drilling operation to reduce tortional forces exerted on the drill string. Thus, an operator was required to continuously monitor the torque generated during the drilling operation and discontinue the drilling operation upon confronting high torque conditions. The drilling operation has been typically sporadic and operating efficiencies have been relatively low.
Additionally, the prior art hydraulic mining apparatus has typically possessed undesirable leakage at the interconnections between the various conduits disposed within the interior of the drill sections. Such leakage causes pressure drops within the cutting jet supply, jet pump supply, and eductor return conduit which adversely affects the mining operation. Thus, there exists a substantial need for an improved drill section which provides sufficient structural integrity at its end connections to prevent twist-off during the drilling operation, lubricate the drill string to reduce the torque exerted during the drilling operation, and provides an effective seal on the multiple conduit extending through the interior of the individual drill sections.